Dogs are even more affectionate and loyal than previously thought. You know when you return home after a whole workday, and your pup is there right at the door, wagging its tail like a propeller and jumping in your lap before you even have a chance to close the door? That genuine affection is an expression of what’s going on inside your dog’s brain. A recent study shows that dogs actually have happy tears when they meet their humans again after a long time apart.
“We found that dogs shed tears associated with positive emotions,” says Professor Takefumi Kikusui of the Azabu University in Japan. Yes, it’s as cute as it sounds - your dog is so happy to see you that it sheds tears of joy. The researchers believe that positive emotions cause a spike of oxytocin in the dog’s brain. Also known as the “love hormone,” oxytocin is believed to also strengthen bonds in dogs - just like in humans.
Professor Kikusui first noticed that dogs shed tears when he noticed a poodle mom nursing her puppies. Her eyes welled up with something that can only be described as “tears of joy.” The researcher then became determined to find out if the same reaction to positive emotions was seen in dogs’ relationships with humans.
In the study, the researchers measured the tear volumes of different dogs before they were separated from their humans. Upon the humans’ return, the tear volume was measured again, revealing that the tear volume was greater after the reunion.
In another round of the experiment, the researchers added oxytocin to dogs' eyes. This too increased their tear volume, confirming the link between positive emotion and tear volume. “We had never heard of the discovery that animals shed tears in joyful situations, such as reuniting with their owners, and we were all excited that this would be a world first!” Kikusui was quoted as saying.
We don’t know about you, but this study had at least one unexpected but positive effect - a sudden urge to hug our pets!